Detection of a gravitational-wave signal of non-astrophysical origin would be a landmark discovery, potentially providing a significant clue to some of our most basic, big-picture scientific questions about the Universe. In this white paper, we survey the leading early-Universe mechanisms that may produce a detectable signal-including inflation, phase transitions, topological defects, as well as primordial black holes-and highlight the connections to fundamental physics. We review the complementarity with collider searches for new physics, and multimessenger probes of the large-scale structure of the Universe.
Keywords: Collider and gravitational wave complementarity; Dark matter; Gravitational wave and EM correlation; Inflation; Phase transitions; Primordial gravitational waves; Topological defects.
© The Author(s) 2022.